1. Field of the Invention
The present invention relates generally to a computer simulation method, and more specifically to a method of simulating a sputter deposition profile when refilling a contact hole formed on a semiconductor wafer. By way of example, the present invention finds excellent advantages when applied to a sputtered aluminum profile computer simulation.
2. Description of the Related Art
As the density of semiconductor device increases, it becomes very important to develop a technology for effectively burying or refilling a conductive material in the miniaturized contact holes.
In order to improve such a technology, Japanese Laid-open Patent Application No. 8-171549 discloses a method of simulating a profile of deposited film using axial symmetry of a contact hole. According to this related art, the portions of a sputter target, from which atoms are emitted, are determined using the Monte Carlo method. Further, the trajectories of particles in a sputter equipment are calculated under the assumption that the energy of emitted particles are determined using the Thompson's equation, and that the emission angular distribution is proportional to "sin .theta. cos .theta.". Still further, the collisions of particles are assumed elastic while assuming that the collision cross-section is constant. Still further, the collision points are determined using random numbers from Poisson's distribution. The trajectories thus determined are successively directed to each of plural coordinate points for calculating sputter deposition while checking to determine if the trajectory is shadowed.
However, according to the above mentioned conventional technique, the shadow judgment is implemented only on an uppermost portion of the sputter deposition. Thus, in the case where the deposited film is thick and the film deposition grows laterally from the side wall of the contact hole, the conventional technique has encountered the drawback that the shadow judgment is not precisely implemented.